NEED ENGINE BUILDER HELP..HAVE A PROBLEM!

[Guest bigjim240z]

I need some help with a freinds engine combo...this is what he has in his 350 that went KABOOM!...350 4 bolt block, stock 350 crank, lunati 6.000 rods, keith black hypereutectic pistons +30 with 30cc d-dish, milodon oil pan with windage tray and crank scraper,roller timing chain, comp cams 224 int, 224 exh, .470 lift @ 50 cam shaft, chevy vortex 350 heads that have been ported and polished, they also have screw in studs and guide plates with harland sharp roller rockers. Not that this makes a difference but he also has the edelbroch intake that work with the vortex heads, everything was balanced too! This should make a very good combo or so we thought..it was in his car for about 1-2 weeks and sounded good, but has no real power like it should. While driving home from work it died and he had it towed home, i went over and yanked off the valve covers and noticed a bent push rod, then i pulled the plugs and noticed a smashed spark plug in the same cylinder. so i yanked the heads and found a hole in the #4 piston and a busted valve along with a cracked cylinder bore. The chamber in the head was also beat to hell(junk head now). with further inspection i noticed all the pistons has a groove in them , the intake valves look like they wore a groove into the piston heads!..so the whole time this engine was running the valves were hitting the pistons. WHAT THE HELL HAPPENED?..His brother built the motor so i have no idea what he did wrong, but i will be putting it back together after he gets a new block, head and piston. what should i look for?..any help is apprecitated..thanks jim

[grumpyvette]

if you want the new engine to last longer please follow these suggestions, if you try and save money and get cheap the same thing is likely to happen again.

 

take it totally apart and have a machine shop clean and inspect the block and flush all the oil passages.

 

have the rods and all the pistons carefully inspected (and personally Id throw the pistons away and get new ones if those valve impact points look at all deep)

 

you will need new rings and bearings

 

you should replace the cam and lifters they took a hell of a beating even if the dammage is not obvious and you must replace the timeing gear set it possitively was dammaged even if it appears ok

 

get the head your thinking of reuseing magnaflux tested and checked for dammage

 

now the most likely CAUSE is that you had the cam timed/installed wrong or you did not check ALL YOUR CLEARANCES. if the cams lift was over about .450 or the durration over about 220@.050 lift than you certainly need to check ALL YOUR CLEARANCES.

 

if you don,t know how to do that get a copy of these books,

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buy these FIVE books, it will be the best money you ever spent, read them, and you will be miles ahead of the average guy.

HOW TO BUILD THE SMALL BLOCK CHEVEROLET by LARRY ATHERTON&LARRY SCHREIB

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HOW TO BUILD MAX PERFORMANCE CHEVY SMALL BLOCKS ON A BUDGET by DAVID VIZARD

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JOHN LINGENFELTER on modifying small-block chevy engines

 

how to build & modify CHEVROLET small-block V-8 CAMSHAFTS & VALVTRAINS BY DAVID VIZARD

 

SMOKEY YUNICK,S POWER SECRETS

 

read them! then after you understand everything and only after you have aworking knowledge of the correct procedures , you can re-assemble the engine

[Guest Anonymous]

What ratio are the roller rockers, if I was guessing I'd bet you found the limits (and a little extra obviously) of the Vortec lift limitations. It probably bound the springs and kissed a piston or two or more. Just a guess, but it sounds like a likely scenario. Second go, follow Grumps excellent advice and maybe use some modeling clay on a piston top next time to see if those valves are close to the pistons before assembly.. Good luck.

 

Regards,

 

Lone